Alarming spread of vancomycin resistant enterococci in Sweden since 2007.

The total number of persons infected or colonised with vancomycin-resistant enterococci mandatorily reported to the Swedish Institute for Infectious Disease Control increased dramatically during 2007 and 2008. During a period of twenty months from 1 July 2007 to 28 February 2009, a total of 760 cases were reported compared with 194 cases reported during the entire period from 2000 to 2006. This rise was mainly attributed to a wide dissemination of vancomycin resistant enterococci which started in a number of hospitals in Stockholm in the autumn of 2007 and was followed by dissemination in various healthcare facilities (hospitals and homes for the elderly) in a further two Swedish counties in 2008. The majority of the cases (97%) were acquired in Sweden and among these, healthcare-acquired E. faecium vanB dominated (n=634). The majority of these isolates had identical or closely related pulsed-field gel electrophoresis patterns indicating clonal dissemination in the affected counties. The median minimum inhibitory concentration of vancomycin was 32 mg/L (ranging from 4 to >128 mg/L) and of teichoplanin 0.12 mg/L (ranging from 0.06 to 0.25 mg/L). Particular emphasis was placed on countermeasures such as screening, contact tracing, cleaning procedures, education in accurate use of infection control practices as well as increasing awareness of hygiene among patients and visitors. With these measures the dissemination rate decreased substantially, but new infections with the E. faecium vanB strain were still detected.

[Epidemic strain of methicillin-resistant Staphylococcus aureus in hospitals of Saint-Petersburg].

AIM: To study genetic characteristics of methicillin-resistant Staphylococcus aureus (MRSA) causing nosocomial infections in specialized inpatient clinics of Saint-Petersburg. MATERIALS AND METHODS: Nine cultures of S. aureus, which caused nosocomial infections in patients of 3 clinics in Saint-Petersburg, were studied by pulse-electrophoresis and spa-sequence typing. Identification of superantigens' genes pvl, sea, seb, sec, tst was performed by PCR. RESULTS: Circulation of epidemic clone BT2007 attributed to spa-type t008 was revealed. According to pulse-electrotype, this epidemic clone was related with European epidemic clones of widespread cluster A. CONCLUSION: Epidemiologic surveillance for MRSA should incorporate monitoring of clonal structure of the agent on both local (intra-clinic) and regional level.

Validity of routine surveillance data: a case study on Swedish notifications of methicillin-resistant Staphylococcus aureus.

Surveillance of communicable diseases is a public health corner stone. Routine notification data on communicable diseases are used as a basis for public health action as well as for policy making. While there are agreed standards for evaluating the performance of surveillance systems, it is rarely possible to analyse the validity of the data entered into these systems. In this study we compared data on all Swedish cases of methicillin-resistant Staphylococcus aureus (MRSA) routinely notified between 2000 and 2003 with follow-up information collected for each of these cases as part of a public health project. The variables Reason for testing (clinical sample, contact tracing, screening of risk group), Clinical presentation (disease, colonisation), Transmission setting (healthcare-acquired, community-acquired), Country of acquisition (Sweden, abroad) and Risk-occupation (yes, no) were analysed for sensitivity, positive predictive value and completeness of answers. The sensitivity varied between 23% and 83%, the positive predictive values were generally higher (55% to 97%), while missing answers varied from 11% to 59%. The proportion of community-acquired cases was markedly higher when excluding either cases of MRSA colonisation or cases found through public health-initiated activities (contact tracing or screening of risk groups). We conclude that the quality of routine surveillance data may be inadequate for in-depth epidemiological analyses. This should be taken into account when interpreting routine surveillance figures. Whether or not the case definition includes cases of MRSA colonisation may have a significant impact on population-wide estimates of MRSA occurrence.

Emergence and spread of vancomycin resistance among enterococci in Europe.

Nowadays, six types of acquired vancomycin resistance in enterococci are known; however, only VanA and to a lesser extent VanB are widely prevalent. Various genes encode acquired vancomycin resistance and these are typically associated with mobile genetic elements which allow resistance to spread clonally and laterally. The major reservoir of acquired vancomycin resistance is Enterococcus faecium; vancomycin-resistant Enterococcus faecalis are still rare. Population analysis of E. faecium has revealed a distinct subpopulation of hospital-acquired strain types, which can be differentiated by molecular typing methods (MLVA, MLST) from human commensal and animal strains. Hospital-acquired E. faecium have additional genomic content (accessory genome) including several factors known or supposed to be virulence-associated. Acquired ampicillin resistance is a major phenotypic marker of hospital-acquired E. faecium in Europe and experience has shown that it often precedes increasing rates of VRE with a delay of several years. Several factors are known to promote VRE colonisation and transmission; however, despite having populations with similar predispositions and preconditions, rates of VRE vary all over Europe.

Short summary of Swedres 2005, a report on Swedish antibiotic utilisation and resistance.

"Swedres 2005", the fifth report on Swedish antibiotic utilisation and resistance in human medicine, was presented in May 2006. Compared with the rest of Europe, antibiotic consumption and resistance levels in Sweden are relatively low. However, global travel and trade facilitate the spread of bacteria between countries and continents. As a consequence, also in Sweden, increasing resistance trends are seen for some pathogens, notably ESBL-producing enterobacteriaceae.

Acetic acid as a decontamination method for sink drains in a nosocomial outbreak of metallo-ß-lactamase-producing Pseudomonas aeruginosa.

BACKGROUND: Pseudomonas aeruginosa may colonize water systems via biofilm formation. In hospital environments, contaminated sinks have been associated with nosocomial transmission. Here we describe a prolonged outbreak of a metallo-ß-lactamase-producing P. aeruginosa (Pae-MBL) associated with sink drains, and propose a previously unreported decontamination method with acetic acid. AIM: To describe a nosocomial outbreak of Pae-MBL associated with hospital sink drains and to evaluate acetic acid as a decontamination method. METHODS: The outbreak was investigated by searching the microbiology database, microbiological sampling and strain typing. Antibacterial and antibiofilm properties of acetic acid were evaluated in vitro. Pae-MBL-positive sinks were treated with 24% acetic acid once weekly and monitored with repeated cultures. FINDINGS: Fourteen patients with positive cultures for Pae-MBL were identified from 2008 to 2014. The patients had been admitted to three wards, where screening discovered Pae-MBL in 12 sink drains located in the patient bathrooms. Typing of clinical and sink drain isolates revealed identical or closely related strains. Pae-MBL biofilm was highly sensitive to acetic acid with a minimum biofilm eradication concentration of 0.75% (range: 0.19-1.5). Weekly treatment of colonized sink drains with acetic acid resulted in negative cultures and terminated transmission. CONCLUSION: Acetic acid is highly effective against Pae-MBL biofilms, and may be used as a simple method to decontaminate sink drains and to prevent nosocomial transmission.

A new dhfrVIII trimethoprim-resistance gene, flanked by IS26, whose product is remote from other dihydrofolate reductases in parsimony analysis.

A new plasmid-borne gene, dhfrVIII, encoding high-level trimethoprim resistance (TpR) was found in an intestinal Escherichia coli. It seems to be a widely occurring mediator of TpR. Among 973 examined TpR E. coli, the new resistance gene was found in 13 (1.3%) isolates from Sweden, Finland and Nigeria. The new gene was sequenced and found to code for a dihydrofolate reductase (DHFR) of 169 amino acids (M(r) 19005). The dhfrVIII gene on the studied plasmid pLMO226 was observed to be flanked by IS26 elements. The dhfrVIII gene and a 3' unidentified open reading frame (ORF) seem to be borne on a compound transposon with IS26 at its ends, since the configuration of two IS26 flanking dhfrVIII and the unidentified ORF was conserved among the isolates that were probe-positive for the gene. Phylogeny parsimony analysis showed the dhfrVIII-encoded enzyme to be only remotely related to other known plasmid-mediated, drug-resistant DHFR. Only a few of the latter form well-supported monophyletic groups.

In vitro activity of norfloxacin and other antibacterial agents against gastro-intestinal pathogens isolated in Sweden.

The in vitro activity of norfloxacin was compared to that of ampicillin, doxycycline, chloramphenicol, trimethoprim in combination with sulfamethoxazole (1/20), and erythromycin, against 272 clinical isolates of gastro-intestinal pathogens. Norfloxacin was the most active compound of those tested with MICs in the range 0.004-2 mg/l. Concentrations inhibiting 90% of the strains (MIC 90) were 0.008 mg/l for Vibrio cholerae, 0.016 mg/l for Aeromonas hydrophila, 0.032 mg/l for Vibrio cholerae non 01, 0.064 mg/l for Vibrio parahaemolyticus, Yersinia enterocolitica 03, enterotoxigenic (ETEC) and enteropathogenic (EPEC) Escherichia coli and Shigella species, 0.125 mg/l for Salmonella species, and 0.5 mg/l for Campylobacter species. Resistance to one or several of the other drugs was seen with higher or lower frequency in all the bacterial species tested. No cross-resistance between any of the other agents and norfloxacin was recorded.

Antimicrobial susceptibility of equine isolates of Actinobacillus spp. and identification of beta-lactamases in some strains.

A total number of 149 Actinobacillus strains isolated from clinical samples (73 strains) and from the oral cavity of healthy horses (76 strains) were tested for their susceptibility to 17 antimicrobial substances. The antibiograms were generally very similar between the various strains and no differences could be clearly correlated to either phenotype or source of isolates. However, when tested against penicillin, ampicillin, trimethoprim-sulfa, and streptomycin, small groups of strains with what appeared to be acquired resistance could be identified. Eight of the penicillin-resistant strains were found to produce beta-lactamase. The beta-lactamases appeared to be bound tightly to the cell wall, thereby frustrating further characterization by isoelectric focusing. Plasmids of approximately 3 kb were found in four out of seven beta-lactamase-producing strains submitted to plasmid analysis.

Clonal analysis of Streptococcus pneumoniae nonsusceptible to penicillin at day-care centers with index cases, in a region with low incidence of resistance: emergence of an invasive type 35B clone among carriers.

The nasopharyngeal carriage rate of potential respiratory pathogens was studied in 36 index children with a pneumococci nonsusceptible to penicillin (PNSP), in 595 healthy children, and in 123 personnel at 16 day-care centers (DCCs) with index cases in the Stockholm area, an urban area with a low incidence of antibiotic resistant pneumococci, during the winter of 1997-1998. The spread and clonality of PNSP, Haemophilus influenzae and Moraxella catarrhalis, were studied by analyzing antibiotic susceptibility and serotype, and for PSNP also by using pulsed-field electrophoresis (PFGE) and multilocus sequence typing (MLST). In contrast to the low carriage rate found among the adult contacts (2%), 40% of the children harbored pneumococci, of which 20% were PNSP. Nasopharyngeal colonization decreased with age. The 49 PNSP isolates consisted of 20 clones, of which 10 could be identified in more than one child attending the same or different DCCs. In five DCCs, we observed a spread of PNSP from the index case. A novel PNSP clone of type 35B, found to cause invasive disease in several states in the United States, was found to emerge among several carriers at two DCCs . A high proportion of PNSP isolates were multiresistant to antibiotics (34%), which has implications for treatment regimens, even in a country like Sweden where the proportion of PNSP currently is low (3-4%). One PNSP clone of type 9V found among the carriers, has been shown to cause invasive disease in Sweden as well as in other countries, suggesting that one reason for the occurrence of invasive PNSP clones may be their ability to colonize and spread among healthy carriers. Other internationally spread antibiotic resistant pneumococcal clones found were of types 9V, 19F, and 23F.

E-Test as a routine MIC tool for reference work.

The usefulness of the E-Test, a method for determining minimum inhibitory concentrations of antibiotics against bacteria, in the reference work of susceptibility testing is described. Examples are given on the establishment of reference collections of bacterial strains and on quality control, areas that should also be valid for routine clinical bacteriology laboratories.

Penetration of fusidic acid and rifampicin into cerebrospinal fluid in low-grade inflammatory meningitis caused by Staphylococcus epidermidis.

Cerebrospinal fluid (CSF) concentration-time curves of rifampicin and fusidic acid were studied in a patient with post-operative meningitis caused by Staphylococcus epidermidis. The patient was treated with this combination of antimicrobial agents because of a severe hypersensitivity reaction to vancomycin. Peak CSF concentrations of rifampicin exceeded the MIC by > 60-fold, while those of fusidic acid just reached the MIC. CSF concentrations of fusidic acid were relatively stable within the range reported for patients with uninflamed meninges, but serum levels were surprisingly low. An increase in the metabolism of fusidic acid induced by rifampicin cannot be excluded.

Clonality among ampicillin-resistant Enterococcus faecium isolates in Sweden and relationship with ciprofloxacin resistance.

OBJECTIVE: To investigate clonal relationships in a nationwide sample of human Enterococcus faecium isolates. METHODS: Biochemical fingerprinting (PhP (PhenePlate) typing) was used to compare 180 fecal ampicillin-resistant E. faecium (ARE) isolates with 169 matched fecal ampicillin-susceptible E. faecium (ASE) isolates from patients in 23 hospitals, collected in 1998, and to study 39 fecal ARE isolates from non-hospitalized individuals collected in 1998, and five ARE and 29 ASE isolates from the early 1990s. Representative ARE and ASE isolates were subjected to pulsed-field gel electrophoresis (PFGE) analysis of genomic DNA and sequencing of the regions encoding the fluoroquinolone targets of the enzymes GyrA and ParC. RESULTS: Both PhP and PFGE results showed a higher homogeneity among ARE than among ASE isolates (P < 0.001). One PhP type (FMSE1) comprised 73% of the hospital ARE isolates (53% of ARE isolates from non-hospitalized individuals, and four of five ARE isolates from the early 1990s), but only 1% of the ASE isolates. PFGE of the hospital E. faecium isolates revealed that 23 of the 25 ARE isolates and one of the 22 ASE isolates were of one dominating type. High-level resistance to ciprofloxacin (MIC > 16 mg/L) was present in 91% of ARE isolates, whereas only low-level resistance (MIC 4-16 mg/L; 35% of isolates) was found among ASE isolates. One mutation in parC (codon 80) and one of two mutations in gyrA (codons 83 or 87) were detected in all ARE isolates tested with high-level ciprofloxacin resistance, but were lacking in ARE and ASE isolates with low-level ciprofloxacin resistance. CONCLUSION: Most ARE isolates in Sweden were clonally related. High-level ciprofloxacin resistance was found in ARE isolates of PhP type FMSE1 as well as in other PhP types, but never in ASE isolates.

Antibiotic sensitivity of enteric pathogens in Vietnam.

The in vitro antimicrobial susceptibilities of 675 common enteropathogenic isolates from faecal specimens of patients with diarrhea (E. coli, Shigella, Salmonella and V. cholerae), and 568 E. coli isolates from faecal flora of healthy persons, which were collected as part of a National antibiotic resistance surveillance in Vietnam, were determined. The agar dilution method was used for the following nine antibiotics: ampicillin, doxycycline, chloramphenicol, gentamicin, nalidixic acid, kanamycin, trimethoprim, trimethoprim in combination with sulfamethoxazole (1/20), and sulfisomidin. Gentamicin was the most active of the antibiotics tested against all bacterial species with MICs in the range 0.125-4 mg/l. All strains were susceptible to nalidixic acid (0.125-8 mg/l) and more than 90% were susceptible to kanamycin. Among E. coli and Shigella isolates from patients the frequencies of resistance to commonly used antibiotics were high: ampicillin 73% and 84%, doxycycline 83% and 94%, chloramphenicol 71% and 91%, sulfisomidin 82% and 92%, respectively. Resistance to trimethoprin, as well as to the combination with sulfamethoxazole was found in 21% and 23%, respectively. The frequencies of multiple resistance (resistance to three or more antibiotics) were also high (77% and 89%, respectively). Less than 10% of Salmonellae and V. cholerae isolates were resistant to ampicillin, sulfisomidin or trimethoprim. Among E. coli from healthy people the frequencies of resistance were lower than in isolates from patients: ampicillin 23%, doxycycline 40%, chloramphenicol 21% and sulfisomidin 34%. However, the same patterns of multiple resistance were found in both groups.

Epidemiology and ecology of enterococci, with special reference to antibiotic resistant strains, in animals, humans and the environment. Example of an ongoing project within the European research programme.

The objectives of the present study are to generate knowledge of the ecology and epidemiology of enterococci in the food chain by studying the following: (1) the population structure (in measures of abundance, number of vancomycin resistant strains, antibiotic resistance patterns, diversity, and stability) among enterococcal populations in different geographical regions and in different links of the food chain (2) possible transmission of strains through the food chain and between hospital environments and the food chain (3) the association between vancomycin resistance and individual strains of enterococci and (4) the diversity of the drug resistance genes in enterococci. So far, 1578 samples have been collected from different countries within the EU (Sweden, Denmark, UK and Spain), and from different habitats (pig farms, carcasses in slaughter houses, soil, manure, water, sewage, and humans). Total and vancomycin resistant enterococcal populations in each sample have been enumerated and more than 12000 isolates have been characterised by phenotyping. Representative isolates are further species identified and characterised by genotyping and MIC determination and from antibiotic resistant isolates the resistance genes are characterised.

Methods for identifying methicillin resistancein Staphylococcus aureus.

Five methods for the detection of methicillin-resistant Staphylococcus aureus were used to examine a collection of 100 clinical isolates comprising both susceptible and resistant strains. The disc diffusion test with oxacillin had a sensitivity of 93.3% and a specificity of 92.0% whereas mannitol salt agar containing oxacillin had a sensitivity of 100% and specificity 80.6% with high inoculum. With a low inoculum the sensitivity was 90.7% and specificity 96.0%. The MRSA screen test (Denka Seiken Co. Ltd., Japan) and Evigene MRSA Detection Kit (State Serum Institute, Denmark) tests were in complete agreement with results obtained with polymerase chain reaction assays amplifying mecA and nuc gene sequences.

Report on the first PVL-positive community acquired MRSA strain in Latvia.

Infections by community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) have been reported worldwide. Here we present characterisation of the first CA-MRSA isolated in Latvia. A PVL-positive ST30-MRSA-IV strain was isolated from a nasal swab and the central venous catheter of a patient with fever and multiple organ failure. The PFGE pattern of this strain was identical to pattern SE00-3 of MRSA isolated in Sweden from 29 patients during 2000-2003. This strain is related to the South Pacific area, and its appearance in Sweden and Latvia demonstrates its global spread.

Report on the first PVL-positive community acquired MRSA strain in Latvia.

Infections by community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) have been reported worldwide. Here we present characterisation of the first CA-MRSA isolated in Latvia. A PVL-positive ST30-MRSA-IV strain was isolated from a nasal swab and the central venous catheter of a patient with fever and multiple organ failure. The PFGE pattern of this strain was identical to pattern SE00-3 of MRSA isolated in Sweden from 29 patients during 2000-2003. This strain is related to the South Pacific area, and its appearance in Sweden and Latvia demonstrates its global spread.

European Antimicrobial Resistance Surveillance System (EARSS): objectives and organisation.

Effective European surveillance must have the agreement and active involvement of all participants, concluded a European Union (EU) conference on the need for surveillance of resistant microorganisms (the microbial threat), held in September 1998 in De